1. Field of Invention
The present invention relates to a device for navigation--particularly of an aircraft--and primarily to a plotter device intended for use in conjunction with information obtained from one or more instrument displays in the cockpit of an airplane.
2. Description of Prior Art
The FAA (Federal Aviation Administration) maintains a system of radio-navigation stations. These radio-navigation stations consist of radio beacons that contain, within their signals, bearing and/or distance information. Such stations are known as V.O.R. (very-high frequency omni-directional range), NDB (non-directional radio beacon), and V.O.R./ TACAN (known as VORTAC, where TACAN is a NATO military system which adds a bearing function to DME, Distance Measuring Equipment), i.e. distance information may be obtained from the TACAN portion of a VORTAC. Pilots of aircraft may have instruments in the aircraft either on the instrument panel or hand-held that provide information of the location of the aircraft relative to the position of one or more radio-navigation stations, through the use of pointers and the like on these instruments.
The N.O.A.A. (National Oceanic and Atmospheric Administration) publishes aeronautical maps that have information about terrain, obstructions, landmarks, rivers, highways, radio-navigation station locations, and other information useful for a pilot. Theses aeronautical maps may be used for the purpose of allowing a pilot to know or determine the position of the aircraft relative to the terrain depictions on the map. Certain of these aeronautical maps provide a blue compass rose (a circle with an indication of magnetic North and the degrees, usually every 5.degree., from magnetic North) circumscribed about the center point of each VOR/VORTAC and VOR/DME radio-navigation station, and a corresponding blue symbol at the center point of said compass rose that marks the type of station, for example VOR, VOR/DME, and VORTAC. The symbols are usually referenced in the map.varies.s legend. Each NDB also has a symbol printed on these maps at each location of the NDB, however, there typically is no printed compass rose for an NDB station. The symbols for the two types of NDB (NDB, NDB/DME) can also be referenced in the map's legend.
While flying an aircraft and navigating a course route via use of radio-navigation aids, the problem for the pilot of an aircraft often is in transposing the information from the instrument display onto an aeronautical map. In large or expensive aircraft this may be done automatically by expensive equipment such as computer systems. This transposing is done so that a graphic depiction of the aircraft's location can be made on the map showing the terrain. The instruments in the aircraft obtain signals from the radio-navigation stations on the ground and are used to plot the location of the aircraft in relation to the bearing and distance from the source of the radio signals which are transmitted from known locations. There are several types of navigational plotters made and sold for the purpose of allowing a pilot to triangulate an aircraft's position based on signals from two or more radio-navigation stations. These plotters are not easy to use and may require too much of a pilot's attention and time during flight. The major problem of these plotters of the prior art is that they require the simultaneous use of both hands to hold the plotter on an aeronautical map and draw the lines for triangulation to determine the location and bearing of the aircraft. The need for frequent triangulation may occur in flight, especially when the flight is conducted in instrument meteorological conditions during which time strict attention must be made to flight instruments in order to avoid unusual attitudes or spatial disorientation. The use of a cumbersome plotting system exacerbates the problem of determining the location and bearing of the aircraft.
The prior art plotters are illustrated by the following patents:
U.S. design patent D269,415 to Paton (Aug. 21, 1983) discloses an ornamental design for a pilot triangulation scale. The design illustrates two arms that are fixed at the ends to the circular members. This fixed attachment of the arms poses the problem when the course of the aircraft is between the two circular members which are assumed to be placed at the location of two radio-navigation stations on a map.
U.S. Pat. No. 4,095,342 to Oertli (Jun. 20, 1978) disclosed a radio navigation aid. This plotter has three compass roses which are preset by reference to a navigational chart to fix the distances and angular bearing between two radio navigational locations and the intended destination. It is clear that this plotter can be used only when two radio navigational locations having strong signals and the destination location is within the distance capabilities of the arms of the device. An extended distance flight is not within the disclosed use of the plotter but requires several devices to be preset for various stages of travel and used in succession. In the event a particular signal from a pre-selected radio navigation station has problems there is no backup suggested in the use of this plotter.
U.S. Pat. No. 4,866,852 to Plier (Sep. 19, 1989) discloses an aeronautic chart course and location locator. The locator is removably attached by means of an adhesive backing to an aeronautical chart.
U.S. Pat. No. 4,879,812 to Rabb (Nov. 14, 1989) discloses an aerial map navigational aid. This device includes two arms that are attached to stick-on discs placed on compass rose stickers on a map. With this device, each arm must be moved separately. Due to the nature of the assembly of this device, if two navigation stations lie close together or the path of fight passes between the stick-on discs placed on the map, the two arms will interfere with each other.
Other navigational patents are:
U.S. design patent D201,385 to Pelletier (Jun. 15, 1965) showing an ornamental design for a navigational plotting instrument. PA1 U.S. design patent D249,656 to Mihail (Sep. 26, 1978) showing an ornamental design for a navigation plotter. PA1 U.S. design patent D250,754 to Gray (Jan. 9, 1979), U.S. Pat. No. 1,942,536 to Clementi (Jan. 9, 1934), U.S. Pat. No. 4,138,817 to Frost et al (Feb. 13, 1979), and U.S. Pat. No. 5,404,648 to Taylor (Apr. 11, 1995) disclose navigation plotters. PA1 U.S. patent D142,051 to White (Aug. 14, 1945) showing an ornamental design for a drafting instrument that is capable of triangulation.
Other patents are:
U.S. design patent D204,805 to Gartman et al (May 17, 1966) showing an ornamental design for a goniometer.
The plotter of the present invention overcomes the inconveniences and deficiencies of the prior art plotters. A pilot or student pilot with only a few hours of flying experience can not afford for safety reasons being diverted away from the hands on operation of the aircraft. Having a plotter that facilitates rapid ability to position, and verify or determine location of an aircraft, is a necessity. Also, having a plotter that accomplishes its job with a minimal amount of required space is another advantage.